offline: Keep persisted channel lastMessageAt consistent with its latest message

[gpunto]

Goal

Backport of #6621 to v6. Channels could be sorted by a stale lastMessageAt when the persisted value lagged the channel's newest visible message, so a row would show a newer message than its position in the list reflected.

Original issue: #6604

Implementation

When persisting a channel, keep lastMessageAt consistent with its last message instead of trusting the stored field, so it never lags behind (nor regresses below) the newest visible message. Same change as #6621, applied to stream-chat-android-offline where the mapper lives on this branch.

Testing

• ChannelMapperTest: added coverage for advancing to a newer message, not regressing when the stored value is newer, and the no-last-message case; updated the existing mapping test.
• spotlessCheck, detekt, apiCheck (no public API change), and the offline testDebugUnitTest suite pass.

Summary by CodeRabbit

• Bug Fixes
  • Improved channel message timestamps to retain the most recent available time.
  • Corrected timestamp handling when the latest message is newer than the channel timestamp.
  • Added coverage for older, newer, and missing message timestamps.

[github-actions]

PR checklist ✅

All required conditions are satisfied:

• Title length is OK (or ignored by label).
• At least one pr: label exists.
• Sections ### Goal, ### Implementation, and ### Testing are filled (or ignored for dependabot PRs).

🎉 Great job! This PR is ready for review.

[github-actions]

SDK Size Comparison 📏

SDK	Before	After	Difference	Status
stream-chat-android-client	5.26 MB	5.32 MB	0.05 MB	🟢
stream-chat-android-offline	5.49 MB	5.53 MB	0.04 MB	🟢
stream-chat-android-ui-components	10.64 MB	10.75 MB	0.11 MB	🟢
stream-chat-android-compose	12.87 MB	12.96 MB	0.09 MB	🟢

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: a1f64815-3aa3-4efe-b57a-2a8857186bc8

📥 Commits

Reviewing files that changed from the base of the PR and between 85adcb6 and 3b736d2.

📒 Files selected for processing (2)

• stream-chat-android-offline/src/main/java/io/getstream/chat/android/offline/repository/domain/channel/internal/ChannelMapper.kt
• stream-chat-android-offline/src/test/java/io/getstream/chat/android/offline/repository/domain/channel/internal/ChannelMapperTest.kt

---

Walkthrough

Channel.toEntity() now preserves the latest timestamp between the channel and its last message. Tests cover newer, older, and absent last-message timestamps.

Changes

Channel timestamp mapping

Layer / File(s)	Summary
Timestamp selection and validation stream-chat-android-offline/src/main/.../ChannelMapper.kt, stream-chat-android-offline/src/test/.../ChannelMapperTest.kt	Channel.toEntity() stores the later timestamp. Tests verify newer messages advance stale values, older messages do not replace newer channel values, and missing messages preserve the channel timestamp.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• GetStream/stream-chat-android#6621: Both changes update Channel.toEntity() and its timestamp mapping tests.

Poem

A rabbit hops through dates in line,
And keeps the latest message time.
Old stamps stay where they belong,
New stamps make the channel strong.
No message? The old time stays—
Thump, thump, mapped in tidy ways!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the offline persistence fix and its purpose: keeping channel lastMessageAt consistent with the latest message.
Description check	✅ Passed	The description explains the goal, implementation, issue context, and testing, while omitting irrelevant UI and checklist details.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/channel-stale-last-message-at-v6

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[aleksandar-apostolov]

LGTM

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud